Dicobaltoctacarbonyl, Co.sub.2 (CO).sub.8, has been widely used as a catalyst for the hydrogenation of olefins, for which reference is made to (a) Major, Horvath, and Pino, J. Molecular Catalysis, 1988, 45, 275, (b) Ungvary and Marko, J. Organometal. Chem., 1981, 219, 397, (c) Ungvary and Marko, Organometallics, 1982, 1, 1120, and (d) Wender, Levine and Orchin, J. Am. Chem. Soc., 1950, 72, 4375); the hydroformylation of olefins, for which reference is made to (a) Wender, Sternberg and Orchin, J. Am. Chem. Soc., 1953, 75, 3041, and (b) Orchin, Kirch and Goldfarb, J. Am. Chem. Soc., 1956, 78, 5450; and the hydrosilation of olefins, for which reference is made to (a) Hilal, Abu-Eid, Al-Subu and Khalaf, J. Molecular Catalysis, 1987, 39, 1, (b) Harrod and Chalk, J. Am. Chem. Soc., 1965, 87, 1133, (c) Chalk and Harrod, J. Am. Chem. Soc., 1965, 87, 1133, (d) Chalk and Harrod, J. Am. Chem. Soc., 1967, 89, 1640, and (e) Baay and MacDiarmid, Inorg. Chem., 1969, 8, 986. In addition, there is one report in the literature describing the catalysis by Co.sub.2 (CO).sub.8 of the ring-opening polymerization of a heterocyclic compound (Chalk, J. Chem. Soc., Chem. Commun., 1970, 847). Chalk has reported that when Co.sub.2 (CO).sub.8 was used as a hydrosilation catalyst employing tetrahydrofuran as a solvent, poly(tetramethylene oxide) resulting from the ring-opening of THF was isolated. A cationic mechanism was proposed as depicted in equation 1 which follows. ##STR1##
Harrod and Smith similarly observed that THF could be ring-opened under hydrosilation conditions using iridium-containing catalysts (Harrod and Smith, J. Am. Chem. Soc., 1970, 92, 2699). However, polymerization was not observed and only the olefin shown in equation 2, which follows, derived from transfer of the trialkylsilyl group to the oxygen of THF followed by ring opening and elimination, was obtained. ##STR2##
In addition, Co.sub.2 (CO).sub.8 -mediated ring-opening reactions of carbon monoxide with epoxides and other heterocyclic compounds has recently been studied, regarding which reference is made to (a) Alper, Arzoumanian, Petrinani and Saldana-Maldonado, 1985, J. Chem. Soc., Chem. Commun., 1985, 340, (b) Alper and Calet, Tetrahedron Letters, 1988, 29, 1763, (c) Wang, Calet and Alper, J. Organ. Chem, 1989, 54, 20, (d) Kang and Weber, Tetrahedron Letters, 1985, 26, 5415, (e) Kang and Weber, Tetrahedron Letters, 1985, 26, 5753, (f) Seki, Hidaka, Murai and Sonoda, Angew, Chem., 1977, 89, 196, (g) Murai and Sonoda, Angew. Chem., Int. Ed., 1979, 18, 837, (h) Murai, Hatayama, Murai and Sonoda, Organometallics, 1983, 2, 1883, (i) Chatani, Fujii, Yamasaki, Murai and Sonoda, J. Am. Chem. Soc., 1986, 108, 7361, (j) Murai, Kato, Murai, Hatayama and Sonoda, Tetrahedron Letters, 1985, 26, 2683, and (k) Murai et al., J. Am. Chem. Soc., 1989, 111, 7938). These reactions require high pressure and high temperatures, and polymerization was not observed in any of these studies. Two examples of these reactions are given in equations 3 and 4 which follow. ##STR3##
Although the prior art includes these few isolated examples of ring-opening reactions of oxygen heterocycles by cobalt octacarbonyl, there appear to be no citations in the literature describing the ring-opening polymerization of oxygen heterocycles, such as epoxides or vinyl ether monomers, by this catalyst.
It is thus an object of the present invention to provide a catalyst mixture for ring-opening polymerization of heterocyclic monomers and polymers which is economical and permits the facile polymerization of these monomers and polymers preferably at room temperature.
It is another object of the present invention to provide a curable composition, which may be a two part kit, including the catalyst mixture for ring-opening polymerization of heterocyclic monomers and polymers, and at least one polymerizable compound which is a monomer or polymer containing a heterocyclic ring including oxygen, nitrogen, or sulfur.
It is still another object of the present invention to provide a method of making a polymeric product by ring-opening polymerization of heterocyclic monomers and polymers, including monomers and polymers of oxygen, nitrogen, and sulfur heterocycles, such as oxygen heterocycles including epoxides and vinyl ether monomers, preferably at about room temperature.